Endothelin increases myofilament Ca2+ sensitivity in alpha-toxin-permeabilized rabbit mesenteric artery.
Endothelin increases myofilament Ca2+ sensitivity in alpha-toxin-permeabilized rabbit mesenteric artery.
复制标题
内皮素可增加 α 毒素透化兔肠系膜动脉中肌丝 Ca2+ 的敏感性。
DOI：
10.1161/01.res.71.4.951
复制
发表时间：
1992
影响因子：
20.1
通讯作者：
vanBreemen,C
中科院分区：
文献类型：
--
作者：
Nishimura,J;Moreland,S;Ahn,HY;Kawase,T;Moreland,RS;vanBreemen,C
本研究旨在探讨内皮素-1(ET-1)在金黄色葡萄球菌毒素通透性血管平滑肌中的收缩机制。用α-毒素通透的兔肠系膜小动脉用于等长或等渗力记录，或用于测定肌球蛋白轻链(MLC)的磷酸化水平。与单独加入钙离子相比，加入100 nM ET-1和10微米GTP显著增强了肌丝对钙的敏感性(EC50，单独加入0.47微米钙和0.13微米钙对ET-1+(GTP)。这种增强的敏感性被GDPβS逆转。加入30微米的cAMP或cGMP可使ET-1引起的收缩在恒定的[Ca~(2+)]时松弛，表明环核苷酸对收缩调节有直接作用。100 nM星状孢子素抑制蛋白激酶C活性可使ET-1+GTP引起的收缩活动减弱，40微米白屈菜红素可显著抑制ET-1+GTP的升高。在0.32微米的Ca~(2+)浓度下，ET-1与GTP合用后，MLC的稳态磷酸化水平显著增加，但其稳态缩短速度水平并未增加。ET-1诱导的MLC磷酸化水平的升高不受[Ca~(2+)]变化的影响，但缩短速度依赖于Ca~(2+)，提示MLC磷酸化水平的升高可能是蛋白激酶C激活的结果，而不是MLC激酶激活的结果。这些结果与ET-1通过G蛋白依赖的途径和随后激活蛋白激酶C来增加肌丝对钙的敏感性的假设是一致的。
This study was designed to investigate the mechanism of endothelin-1 (ET-1) contractions in Staphylococcus alpha-toxin-permeabilized vascular smooth muscle. Rabbit small mesenteric arteries permeabilized with alpha-toxin were mounted for isometric or isotonic force recording or were processed for determination of myosin light chain (MLC) phosphorylation levels. Addition of 100 nM ET-1 plus 10 microM GTP significantly enhanced myofilament Ca2+ sensitivity as compared with the addition of Ca2+ alone (EC50, 0.47 microM Ca2+ for Ca2+ alone and 0.13 microM Ca2+ for ET-1 plus (GTP). This enhanced sensitivity was reversed by GDP beta S. ET-1-induced contractions were relaxed at a constant [Ca2+] by the addition of 30 microM cAMP or cGMP, demonstrating a direct effect of the cyclic nucleotides on contractile regulation. Inhibition of protein kinase C activity by 100 nM staurosporine relaxed ET-1 plus GTP-induced contractions, and pretreatment with 40 microM chelerythrine inhibited the ET-1 plus GTP increase in force. At 0.32 microM Ca2+, steady-state levels of shortening velocity were not increased by ET-1 plus GTP, although steady-state levels of MLC phosphorylation were significantly enhanced. The ET-1-induced increase in MLC phosphorylation was not altered by changes in [Ca2+], whereas the shortening velocity was Ca2+ dependent, suggesting that the increase MLC phosphorylation level may be the result of protein kinase C, rather than MLC kinase, activation. These results are consistent with the hypothesis that ET-1 increases myofilament Ca2+ sensitivity by a G protein-dependent pathway and subsequent activation of protein kinase C.(ABSTRACT TRUNCATED AT 250 WORDS)